Injection Cycle Refrigerant Control for Compressor Superheat
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Solution Overview
Problem
Air conditioners operating in an injection cycle face challenges with inadequate refrigerant flow rates and superheating of refrigerants, leading to operational errors and unreliable compressor performance, especially under high temperature and low outdoor temperature conditions.
Innovation Solution
The air conditioner adjusts its compressor operation frequency and main expansion valve opening degree based on real-time refrigerant state information to ensure adequate refrigerant flow and prevent superheating, using a controller to manage the injection expansion valve and maintain reliable compressor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the injection expansion valve is opened to improve refrigerant flow in the injection cycle, then the compression performance and heating performance improve, but under specific circumstances (high inlet water temperature and low outdoor temperature) a sufficient amount of refrigerant may not flow through the injection expansion valve, causing compressor discharge temperature to increase and repeated on-off cycling
Solution Approach 1:
The patent introduces a bypass flow path that serves as an intermediary route for refrigerant flow. When the injection expansion valve cannot provide sufficient refrigerant flow under specific conditions (high inlet water temperature and low outdoor temperature), the bypass flow path allows refrigerant to reach the injection port through an alternative route, preventing compressor discharge temperature increase and repeated on-off cycling while maintaining compression performance
Solution Approach 2:
The system dynamically adjusts operating parameters based on detected conditions. When insufficient refrigerant flow is detected through the injection expansion valve, the control unit changes the operation state by activating the bypass flow path, thereby changing the refrigerant flow parameters to maintain reliable compressor operation
2Productivity
If the compressor operation frequency is increased to improve cooling/heating efficiency, then the productivity increases, but the refrigerant flow rate may become insufficient leading to superheating of refrigerants and operational errors
Solution Approach 1:
The control unit continuously monitors refrigerant flow conditions and compressor operation parameters. When insufficient refrigerant flow or superheating conditions are detected, the system provides feedback by adjusting the compressor operation frequency or activating the bypass flow path, thereby maintaining reliable operation while preserving cooling/heating efficiency
Solution Approach 2:
The system dynamically adjusts the compressor operation frequency based on real-time refrigerant flow conditions. The operation frequency is not fixed but varies according to the detected refrigerant state, allowing the system to maintain high efficiency when conditions permit while preventing superheating and operational errors when refrigerant flow becomes insufficient
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This adjustment ensures a stable refrigerant flow rate, prevents superheating, and reduces operational errors, allowing the air conditioner to drive the compressor reliably and maintain efficient performance during injection cycles.
Implementation Method 1
an injection expansion valve and an inner heat exchanger. Specifically, a pipe connecting the indoor heat exchanger and the outdoor heat exchanger is branched, and the branched pipe connects to an injection port disposed at the compressor. The injection expansion valve configured to expand refrigerants is installed in the branched pipe
Implementation Method 2
the inner heat exchanger allows of heat exchange of refrigerants expanded by the injection expansion valve
Implementation Method 3
Refrigerants are compressed in the compressor 10. That is, as a result of driving of the compressor 10, heat is applied to refrigerants, and low-pressure low-temperature gaseous refrigerants are changed into high-pressure high-temperature gaseous refrigerants
Implementation Method 4
The heat of the refrigerants dissipates in the condenser 20. That is, the high-pressure high-temperature gaseous refrigerants are changed to high-pressure middle-low temperature liquid refrigerants (i.e., a phase transition)
Implementation Method 5
The heat of the refrigerants is absorbed (evaporated) in the evaporator 60. That is, the low-pressure low-temperature liquid refrigerants are changed to low- pressure low-temperature gaseous refrigerants
Data Source
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AI summary
The present disclosure relates to an air conditioner and a control method thereof. When operating in an injection cycle, the air conditioner may adjust at least one of an operation frequency of a compressor and an opening degree of a main expansion valve to ensure an adequate flow rate of branch refrigerants flowing to an injection flow path, thereby preventing superheating of refrigerants discharged from the compressor and an operation error of the air conditioner.